The objectives are to: (1) investigate the transactional behavior of mothers and fathers with boy and girl infants during the first year of life. (2) examine the relationships between parent-infant transactions and infant competence at age one. Fifty families, half with first-born of each sex, will be videotaped in a structured play situation seven times, six weeks apart, beginning at baby's 13 weeks. Tapes will be coded using elements of the Escalona-Corman procedures, Watts' Home Scale and the Florida Reciprocal Categories System. The various combinations of circumstances (sex of parent, sex of child, age of child) will be examined to test whether there are differences in the frequencies of observed behavior as a function of the combinations of sex of parent and child. Four factors of infant competence at age one, derived from the Bayley Scale, and a local measure will be dependent variables against which observed behaviors at each age will be correlated to determine the relationships between the behavior of parents and children and these measures.